In a new study involving more than 4 million Danish adults identified though a national health registry, people with rheumatoid arthritis were 40% more likely to have atrial fibrillation than the general population and 30% more likely to suffer a stroke.

Patients with rheumatoid arthritis are known to have a higher heart attack risk, but studies examining the impact of the inflammatory joint disease on stroke have been inconsistent, says researcher Jesper Lindhardsen, MD, of Copenhagen University Hospital Gentofte.

“In our study, rheumatoid arthritis was associated with an increased incidence of atrial fibrillation and stroke,” he says, adding that if inflammation is driving this link then drugs that control inflammation may also reduce stroke risk.

Rheumatoid Arthritis, Atrial Fibrillation

About 2 million Americans have atrial fibrillation, a condition characterized by an erratic heartbeat and the failure of the heart to effectively pump blood.

People with atrial fibrillation are more likely to have a stroke than people without the condition.

In the new study, published in the journal BMJ, Lindhardsen and colleagues examined atrial fibrillation and stroke risk in Danish adults followed for an average of five years.

About two-thirds of more than 18,000 rheumatoid arthritis patients identified in the study were women, and the average age of the patients at the time of diagnosis was 59.

The increase in atrial fibrillation and stroke risk among rheumatoid arthritis patients was most pronounced among patients who were younger than 50. In these patients, having rheumatoid arthritis was associated with about a threefold increase in risk for both conditions.

The researchers conclude that rheumatoid arthritis patients should be screened for atrial fibrillation.

“The [added] risk of stroke in rheumatoid arthritis adds significantly to existing evidence, and the novel finding of an increased incidence of atrial fibrillation suggests that this arrhythmia is relevant in the [heart disease and stroke] risk assessment of these patients,” they write.